Scientists challenge conventional wisdom to improve predictions of the bootstrap current at the edge of fusion plasmas

Simulation shows trapped electrons at left and passing electron at right that are carried in the bootstrap current of a tokamak. Credit: Kwan Liu-Ma, University of California, Davis.

Simulation shows trapped electrons at left and passing electron at right that are carried in the bootstrap current of a tokamak. Credit: Kwan Liu-Ma, University of California, Davis.

Researchers at the U.S. Department of Energy’s (DOE) Princeton Plasma Physics Laboratory (PPPL) have challenged understanding of a key element in fusion plasmas. At issue has been an accurate prediction of the size of the “bootstrap current” — a self-generating electric current — and an understanding of what carries the current at the edge of plasmas in doughnut-shaped facilities called tokamaks. This bootstrap-generated current combines with the current in the core of the plasma to produce a magnetic field to hold the hot gas together during experiments, and can produce stability at the edge of the plasma. Read more

04. May 2016 by Christopher Cane
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Stewart Prager, PPPL Director, Testifies Before U.S. House Subcommittee on Energy

(Photo by Elle Starkman/PPPL Office of Communications) Stewart Prager

(Photo by Elle Starkman/PPPL Office of Communications)
Stewart Prager

Written Testimony of Stewart Prager, Director, Princeton Plasma Physics Laboratory, Professor of Astrophysical Sciences, Princeton University
Delivered to the Committee on Science, Space and Technology Subcommittee on Energy For the hearing on April 20, 2016 Read more

25. April 2016 by Christopher Cane
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Princeton graduate student Imène Goumiri creates computer program that helps stabilize fusion plasmas

(Photo by Elle Starkman/Office of Communications) Imène Goumiri led the design of a controller.

(Photo by Elle Starkman/Office of Communications)
Imène Goumiri led the design of a controller.

Imène Goumiri, a Princeton University graduate student, has worked with physicists at the U.S. Department of Energy’s (DOE) Princeton Plasma Physics Laboratory (PPPL) to simulate a method for limiting instabilities that reduce the performance of fusion plasmas. The more instabilities there are, the less efficiently doughnut-shaped fusion facilities called tokamaks operate. The journal Nuclear Fusion published results of this research in February 2016. The research was supported by the DOE’s Office of Science. Read more

21. April 2016 by Christopher Cane
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PPPL scientists help test innovative device to improve efficiency of tokamaks

(Photo by J.S. Hu ) Photo of white-hot limiter glowing in contact with the plasma during an EAST discharge.

(Photo by J.S. Hu )
Photo of white-hot limiter glowing in contact with the plasma during an EAST discharge.

Scientists at the U.S. Department of Energy’s Princeton Plasma Physics Laboratory (PPPL) have helped design and test a component that could improve the performance of doughnut-shaped fusion facilities known as tokamaks. Called a “liquid lithium limiter,” the device has circulated the protective liquid metal within the walls of China’s Experimental Advanced Superconducting Tokamak (EAST) and kept the plasma from cooling down and halting fusion reactions. The journal Nuclear Fusion published results of the experiment in March 2016. The research was supported by the DOE Office of Science. Read more

12. April 2016 by Christopher Cane
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Physicist Tyler Abrams models lithium erosion in tokamaks

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(Photo by Tyler Abrams) Physicist Tyler Abrams

The world of fusion energy is a world of extremes. For instance, the center of the ultrahot plasma contained within the walls of doughnut-shaped fusion machines known as tokamaks can reach temperatures well above the 15 million degrees Celsius core of the sun. And even though the portion of the plasma closer to the tokamak’s inner walls is 10 to 20 times cooler, it still has enough energy to erode the layer of liquid lithium that may be used to coat components that face the plasma in future tokamaks. Scientists thus seek to know how to prevent hot plasma particles from eroding the protective lithium coating. Read more

05. April 2016 by Christopher Cane
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PPPL engineers design and build state-of-the-art controller for AC to DC converter that manages plasma in upgraded fusion machine

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PPPL scientists Robert Mozulay and Weiguo Que

The electric current that powers fusion experiments requires superb control. Without it, the magnetic coils the current drives cannot contain and shape the plasma that fuels experiments in doughnut-shaped tokamaks correctly. Read more

10. March 2016 by Christopher Cane
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Plasma 101

10 Facts You Should Know About Plasma

The Aurora Borealis (Northern Lights) (Photo by Philippe Moussette for Nasa.gov)

The Aurora Borealis (Northern Lights) (Photo by Philippe Moussette for Nasa.gov)

  1. It’s the fourth state of matter: Solid, liquid, gas, and plasma. Plasma is a super-heated gas, so hot that its electrons get out of the atom’s orbit and roam free. A gas thus becomes a plasma when extreme heat causes its atoms to shed their electrons. Read more

01. March 2016 by Christopher Cane
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A Q&A With the Director of the Princeton Plasma Physics Laboratory, Dr. Stewart Prager

Stewart Prager GrayFusion is the energy source of our sun and the stars. In a fusion reaction, two atomic nuclei fuse and produce very fast-moving particles. Read more

18. February 2016 by Christopher Cane
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PPPL physicists win Torkil Jensen Award to conduct key experiments on DIII-D

Egemen Kolemen and Luis Delgado-Aparicio at PPPL (Photo by Elle Starkman/Office of Communications)

Egemen Kolemen and Luis Delgado-Aparicio at PPPL (Photo by Elle Starkman/PPPL Office of Communications)

Physicists Luis Delgado-Aparicio and Egemen Kolemen of the U.S. Department of Energy’s (DOE) Princeton Plasma Physics Laboratory (PPPL) have won a national scientific competition to conduct a full day of experiments on the DIII-D National Fusion Facility that General Atomics operates in San Diego for the DOE. The honor, known as the Torkil Jensen Award, is named after the late and internationally recognized scientist who was a member of the General Atomics Fusion Group for 44 years. Read more

04. January 2016 by Christopher Cane
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Using powerful computers, physicists uncover mechanism that stabilizes plasma within tokamaks

FigureB

A cross-section of the virtual plasma showing where the magnetic field lines intersect the plane. The central section has field lines that rotate exactly once.

A team of physicists led by Stephen Jardin of the U.S. Department of Energy’s Princeton Plasma Physics Laboratory (PPPL) has discovered a mechanism that prevents the electrical current flowing through fusion plasma from repeatedly peaking and crashing. This behavior is known as a “sawtooth cycle” and can cause instabilities  within the plasma’s core. The results have been published online in Physical Review Letters. The research was supported by the DOE Office of Science. Read more

17. November 2015 by Christopher Cane
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